html,body{
    margin: 0;
    height: 100%;
}
body{
    display: flex;
    justify-content: center;
    align-items: center;
}
.btn{
    width: 390px;
    height: 300px;
    color: rgba(4, 2, 2, 0.72);
    background: linear-gradient(0deg, rgba(0, 177, 242, 0.14) 0%, rgba(2, 146, 251, 0.4) 100%);
    font-family: 'Lato', sans-serif;
    font-weight: 500;
    border-radius: 10px;
    box-shadow: inset 2px 2px 2px 0px rgba(255, 255, 255, .5),
    7px 7px 20px 0px rgba(0, 0, 0, .1),
    4px 4px 5px 0px rgba(0, 0, 0, .1);
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    margin-left: 40px;
    border-left: 10px;
    position: relative;
    line-height: 300px;
    padding: 0;
}
.btn span{
    position: relative;
    display: block;
    width: 100%;
    height: 100%;
    font-size: 48px;
}
.btn::before,.btn::after{
    position:absolute;
    content: '';
    top: 0;
    right: 0px;
    background: rgba(2, 126, 251, 1);
    transition: all 0.3s ease;
}
.btn::before{
    width: 0;
    height: 2px;
}
.btn::after{
    height: 0;
    width: 2px;
}
.btn span::before,
.btn span::after{
    position:absolute;
    content: '';
    bottom: 0;
    left: 0;
    background: rgba(2, 126, 251, 1);
    transition: all 0.3s ease;
}
.btn span::before{
    width: 0;
    height: 2px;
}
.btn span::after{
    height: 0;
    width: 2px;
}

.btn:hover{
    background: transparent;
    color: rgba(2, 126, 251, 1);
}

.btn:hover::before{
    width: 100%;
}
.btn:hover::after{
    height: 100%;
}
.btn span:hover::before{
    width: 100%;
}
.btn span:hover::after{
    height: 100%;
}
